PPAPI: Get TrackedCallback ready for running on non-main threads.

ppapi/proxy/ppb_graphics_2d_proxy.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ppapi/proxy/ppb_graphics_2d_proxy.h"
 
 #include <string.h>  // For memset.
 
 #include "base/compiler_specific.h"
 #include "base/logging.h"
@@ skipping 47 matching lines @@
     return PluginDispatcher::GetForResource(this);
   }
 
   static const ApiID kApiID = API_ID_PPB_GRAPHICS_2D;
 
   PP_Size size_;
   PP_Bool is_always_opaque_;
   float scale_;
 
   // In the plugin, this is the current callback set for Flushes. When the
-  // pointer is non-NULL, we're waiting for a flush ACK.
+  // callback is pending, we're waiting for a flush ACK.
   scoped_refptr<TrackedCallback> current_flush_callback_;
 
   DISALLOW_COPY_AND_ASSIGN(Graphics2D);
 };
 
 Graphics2D::Graphics2D(const HostResource& host_resource,
                        const PP_Size& size,
                        PP_Bool is_always_opaque)
     : Resource(OBJECT_IS_PROXY, host_resource),
       size_(size),
@@ skipping 81 matching lines @@
   if (TrackedCallback::IsPending(current_flush_callback_))
     return PP_ERROR_INPROGRESS;  // Can't have >1 flush pending.
   current_flush_callback_ = callback;
 
   GetDispatcher()->Send(new PpapiHostMsg_PPBGraphics2D_Flush(kApiID,
                                                              host_resource()));
   return PP_OK_COMPLETIONPENDING;
 }
 
 void Graphics2D::FlushACK(int32_t result_code) {
-  TrackedCallback::ClearAndRun(&current_flush_callback_, result_code);
+  current_flush_callback_->Run(result_code);
 }
 
 PPB_Graphics2D_Proxy::PPB_Graphics2D_Proxy(Dispatcher* dispatcher)
     : InterfaceProxy(dispatcher),
       callback_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {
 }
 
 PPB_Graphics2D_Proxy::~PPB_Graphics2D_Proxy() {
 }
 
@@ skipping 119 matching lines @@
 
 void PPB_Graphics2D_Proxy::SendFlushACKToPlugin(
     int32_t result,
     const HostResource& graphics_2d) {
   dispatcher()->Send(new PpapiMsg_PPBGraphics2D_FlushACK(kApiID, graphics_2d,
                                                          result));
 }
 
 }  // namespace proxy
 }  // namespace ppapi